1. Field of the Invention
The present invention belongs to a liquid crystal display technology field, and more particular to a Lower-Temperature-Polycrystal-Silicon (LTPS) Thin-Film-Transistor (TFT) array substrate and a liquid crystal display panel having the same.
2. Description of Related Art
With the development of optical and semiconductor technology, the Flat Panel Display (FPD) also develops vigorously. In many types of the Flat Panel Display, the Liquid Crystal Display (LCD) has become the mainstream of the market because of superior characteristics of high space utilization efficiency, low power consumption and low electromagnetic interference.
Currently, an amorphous silicon thin film transistor (a-Si TFT) is widely used as a switching element of the LCD. However, a a-Si TFT LCD is limited for satisfying the requirements of thin, lightweight, high-definition, high brightness, high reliability, low power consumption. Comparing with the a-Si TFT LCD, a Lower-Temperature-Polycrystal-Silicon (LTPS) TFT LCD has an obvious advantage for satisfying the above requirements.
In a current LTPS-TFT LCD, a liquid crystal display panel formed by a color-filter substrate (referred to as CF substrate) and an array substrate aligned with each other is usually provided. In the liquid crystal display panel, in order to prevent an edge of a pixel from light leakage, a black matrix (referred to as BM) on the CF substrate is usually utilized to shield an edge of a pixel. At the same time, when a light enters from a side of the CF substrate, the black matrix can also prevent a decreasing contrast ratio problem because of a reflective light of a source/drain metal layer on the array substrate. Accordingly, when the CF substrate and the array substrate are aligned, an alignment precision of the black matrix and the source/drain metal layer should be considered. Under the current process capability, an alignment deviation of the black matrix and the source/drain metal layer will be generated. Sometimes, the alignment deviation reaches ±5 μm such that apertures ratio for pixels of the liquid crystal display panel manufactured by the current process capability exist great difference in order to affect a quality of a liquid crystal display panel.